Short-term Outcomes of Hip Arthroscopy for the Treatment of Femoroacetabular Impingement and Labral Tears in Underweight Patients

Background: Being underweight or malnourished has been recognized as an adverse prognostic factor in various surgical orthopaedic interventions. Purpose: (1) To report minimum 2-year outcomes of underweight patients who underwent primary hip arthroscopy for femoroacetabular impingement (FAI) and labral tears and (2) to compare these results with a propensity-matched control group of patients with normal weight. Study Design: Case series; Level of evidence, 4. Methods: Data were retrospectively analyzed for patients with a body mass index (BMI) ≤18.5 kg/m 2 who underwent primary hip arthroscopy by the senior surgeon at a single institution as treatment for FAI and labral tears between August 2008 and January 2022. Included patients had complete pre- and postoperative patient-reported outcomes (PROs) and visual analog scale (VAS) score for pain at minimum 2-year follow-up. Clinically important thresholds for hip arthroscopy, revision surgery, and conversion to total hip arthroplasty were included in the analysis. Patients were propensity matched to a control group of normal weight patients (BMI, 18.6-24.99 kg/m 2 ) in a 1:2 ratio based on sex, age at surgery, acetabular Outerbridge grade, labral treatment, and capsular treatment. Results: A total of 234 patients were included in the study. Underweight patients displayed significant improvements across all PROs and high patient satisfaction. When underweight patients were compared with a benchmark control group, similar magnitudes of improvement were observed at a minimum 2-year follow-up for modified Harris Hip Score, Nonarthritic Hip Score, International Hip Outcome Tool-12, and VAS. Furthermore, the study cohort had a lower magnitude of improvement for the Hip Outcome Score–Sports-Specific Subscale (HOS-SSS) ( P < .05). The study group reached Patient Acceptable Symptom State for HOS-SSS at lower rates. Underweight patients had a higher frequency of revision hip arthroscopy with a relative risk of 2.16 ( P < .05). Conclusion: Hip arthroscopy for the treatment of FAI and labral tear in underweight patients yielded significant short-term improvements in PROs, which, except for postoperative VAS pain score and change in HOS-SSS, were comparable with a benchmark matched control group of normal weight patients. However, underweight patients had a 2.16-fold increased relative risk for revision hip arthroscopy. Underweight patients may benefit from preoperative nutritional evaluation.